The ozonation of drinking water is attractive for small communities that employ local wells or surface water sources provided it can be done at a reasonable cost. Although chlorine is widely used and is cheaper to use that ozone, its use results in the formation of carcinogenic trihalomethanes. Also chlorine has been found to be ineffective in the treatment of Cryptosporidium and viruses. Under an SBIR Phase I grant from the NIH, Compact Membrane Systems (CMS) demonstrated at lab-scale that CMS' membrane technology could be used to effectively ozonate water contaminated with organics, Cryptosporidium, humic acidd, bacteria, and viruses. Recently, CMS identified an ozone hybrid process that is 50-400 times more effective than ozone alone in destroying organic contaminants (no data yet on biologicals). In Phase I, CMS will build and evaluate this hybrid system for removal of Cryptosporidium, nitrobenzene, and humic acid. Long term (7+ days) testing and economic evaluations combined with hybrid system performance will provide understanding of system potential for enhancing cost effective production of quality non-carcinogenic (trihalomethane) drinking water. Focus will be initially on smaller facilities (serving 50, 000 people or less). PROPOSED COMMERCIAL APPLICATION: The proposed ozone hybrid system will provide clean drinking water free of organics, Cryptosporidium, humic acids, bacteria, and viruses in a cost effective way for small communities.